DNA is the molecule that carries genetic information of a given organisms. Genetic variation is the changes that occur in the genome of an organisms to help an organism adapt well to the environment, however, they might also be disadvantageous. The variation in DNA sequences are useful in building a tree of life because DNA sequences are similar in closely related organisms and less similar in less closely related organisms.
Answer: A. mechanisms for which activity is primarily triggered and shaped by the incoming stimulus information.
Explanation:
Bottom-up mechanism is a process in which a body perceives an incoming stimulus and certain physiological changes occurs in the body working in the direction of upwards that is the signals are transferred to the brain so that the brain could interpret the stimulus. This mechanism suggests the fact that our perceptual experience is based upon the sensory stimuli.
Jet streams are fast moving air currents much like how a river is a fast moving water current so the answer is jet streams.
Soil creation is a result of carrying out successions. Succession is the process in which land that is inhabitable by organisms is reclaimed and made fertile. This is done using pioneer species, which do not require soil to grow. After a while, these species are removed and a secondary succession is carried out. After this process, soil is created and the land becomes fertile.